import java.util.Scanner;

public class demo7 {
    public static void main(String[] args) {
        Scanner b = new Scanner(System.in);
        while (b.hasNextLine()) {
            String c = b.nextLine();

            int[] count = new int[26];
            int i = 0;
            char ch = 0;
            for (i = 0; i < c.length(); i++) {
                ch = c.charAt(i);
                count[ch - 97]++;
                if (count[ch - 97] == 1) {
                    System.out.println(ch);
                }

            }

        }
    }
    public static void main11(String[] args) {
        String a="efzhnezlm";
        boolean[]flag=new boolean[26];
        int i=0;
        char ch=0;
        for(i=0;i<a.length();i++)
        {
            ch=a.charAt(i);
            if(flag[ch-97]==false)
            {
                System.out.println(ch);
                flag[ch-97]=true;
            }
        }
    }
    public static void main9(String[] args) {
        StringBuilder a=new StringBuilder("i love love you");
        int d=a.lastIndexOf("love");
        System.out.println(d);
    }
    public static void main8(String[] args) {
        StringBuilder a=new StringBuilder("i love you");
        int d=a.indexOf("love");
        System.out.println(d);
    }
    public static void main7(String[] args) {
        StringBuilder a=new StringBuilder("i love you");
        int c=a.indexOf(" ",2);
        System.out.println(c);
    }
    public static void main6(String[] args) {
        StringBuilder a=new StringBuilder("i love you");
        int b=a.indexOf(" ");
        System.out.println(b);
    }
    public static void main5(String[] args) {
        StringBuilder a=new StringBuilder("i love you");
        a.insert(1," foreve");
        System.out.println(a);
    }
    public static void main4(String[] args) {
        StringBuilder a=new StringBuilder("helloworld");
        System.out.println(a.reverse());
    }
    public static void main3(String[] args) {
        StringBuilder a=new StringBuilder("helloworld");
        a.setCharAt(0,'w');
        System.out.println(a.toString());
    }
    public static void main2(String[] args) {
        StringBuilder a=new StringBuilder("helloworld");
        //a.charAt(1);
        System.out.println(a.charAt(1));

    }
    public static void main1(String[] args) {
        StringBuilder a=new StringBuilder("abc");
        a.append("heelo");
        System.out.println(a.toString());
    }
}
